In most computer network systems, including particularly the World-Wide Web and other forms of communication over the Internet, text is conveyed using the Latin alphabet or variants thereof. The systems are designed to support writing and reading from left to right. Similarly, common computer operating systems, such as the standard Microsoft Windows system, are designed for left-to-right text operation.
Variants of standard operating systems and Web software have been developed to afford bi-directional support and fonts for languages such as Arabic, Hebrew and Japanese. For example, special Windows operating systems are offered with National Language Support (NLS), which typically allows a user to switch back and forth between English and foreign language fonts and between left-to-right (LTR) and right-to-left (RTL) text operation. Some Web browsers also offer NLS. Computers sold with NLS operating systems generally have keyboards on which both the Latin and appropriate foreign language characters are printed. NLS must be pre-installed on the user's computer, and does not offer a solution to a user who wishes to read a foreign-language document or access a Web site without having the particular language support on his or her computer.
Two types of fonts are used for transmission and display of RTL text on the Web: logical fonts and visual fonts, which are also known as Web fonts. Logical fonts are used on bi-directional language support and font styles already present in the user's NLS operating system and/or browser. They can thus operate only in a NLS environment and are written to the computer display from right to left. Visual fonts also require that the font characters be installed on the user's computer, but do not require the computer to have NLS. Instead, special Hypertext Mark-up Language (HTML) code is used to select the foreign language characters and to write them to the computer display in RTL order, even though the letters must be entered in LTR order on the HTML page itself. If the user's computer has neither logical nor visual font support installed, the only way to transmit and display foreign language text is in graphic form, which is slow and inconvenient.
Thus, a user who wishes to view a Web page with Hebrew language text, for example, will generally be unable to do so unless the appropriate type of Hebrew language support has been installed on his or her computer. Furthermore, even if the user has Hebrew NLS installed, Hebrew Web texts will frequently be displayed in LTR order, rather than the appropriate RTL, because the user's browser is attempting to read a visual font as a logical font, or vice versa.
On-screen keyboards have been developed for users who wish to enter Hebrew characters from a computer that does not have Hebrew NLS. Such a keyboard is available, for example, at the “Snunit” Web site of the Hebrew University of Jerusalem (www.snunit.k12.il). A user selects characters from the keyboard by means of mouse clicks and can thus generate a line of text in web font form.